Digital images of geographic areas, such as satellite images, aerial images, images from the perspective of a ground level (e.g. street level images), and other images of a geographic area of interest, are often used as part of a geographic information system. Geo-referencing or alignment of the digital images with specific geographic coordinates can allow for the use of the digital images in surveying, mapping, and other applications. To improve the accuracy of the information associated with the digital images, it can be desirable to associate very accurate longitude, latitude, and/or altitude coordinates to one or more points depicted in the digital image.
Alignment of digital geographic images can include manually measuring ground truth data (e.g. manually measured latitude and longitude coordinates) at an easily visible point, such as a sidewalk corner, depicted in the digital geographic image. The measured ground truth data can then be associated with a specific pixel depicting the visible point in the digital geographic image. For instance, the pixel depicting the sidewalk corner can be identified and the measured ground truth data can be associated with the identified pixel. The association of measured ground truth data with a specific pixel depicted in the image provides an accuracy of at best about 0.5 pixels. For digital geographic imagery having a resolution of about 50 cm×50 cm pixels, this accuracy is at best about 25 cm of accuracy. Typical surveying techniques, however, can provide much higher accuracy, such as within about 2 cm to about 3 cm of accuracy.